Check the airtightness of the test tube first (there is a rubber stopper at the mouth of the test tube and a catheter on it)
Then fill in the potassium permanganate medicine, and put a ball of cotton at the mouth of the test tube (to prevent the potassium permanganate particles from getting into the test tube)
The alcohol lamp moves back and forth at the bottom of the test tube first, so that it is heated uniformly (or else the tube will break), and then concentrate on heating the medicine.
Stick the catheter into the sink and wait for the bubbles to come out continuously and evenly before collecting the gas by the drainage method (otherwise the oxygen collected will not be pure)
When the bubbles come out on the other side of the cylinder, stop the collection and cover the cylinder with a piece of hairy glass and place it squarely on the table.
Finally move the catheter out of the water before extinguishing the alcohol lamp (otherwise the water will back up and rupture the test tube)
Finally give me the points ！！！！！！！